SAN DIEGO — The Obama administration's top cops and their Mexican counterparts are looking for ways to stop arms smuggling across the border as well as new strategies for fighting the drug cartels that have fueled violence in both countries.

Homeland Security Secretary Janet Napolitano and Attorney General Eric Holder were set to meet Thursday with Mexican Attorney General Eduardo Medina-Mora and Interior Minister Fernando Gomez-Mont in Cuernavaca, Mexico.

The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives has traced 95 percent of the weapons seized at the scenes of Mexican drug violence back to the U.S. The weapons are growing in power and include .50-caliber Barrett rifles and ammunition that can pierce the armor of Mexican soldiers and police.

The Obama administration has promised a crackdown on illegal U.S. weapons sales that supply the drug cartels. And Mexico is acknowledging shortcomings on its side of the 2,000-mile border.

Around noon Tuesday at the San Ysidro land port between San Diego and Tijuana, there was an approximate 45-minute wait for vehicles coming from Mexico to the U.S. because of the security measures. But at the same time, cars were zipping across the U.S. border into Mexico with little security on the Mexican side.

Facilitating legal trade, not catching gun smugglers, has been the prime directive, Mexican officials have said. Now, the cartel security threat demands a new approach.

Mexican officials say the violence spawned by warring drug cartels killed 6,290 people last year and more than 1,000 so far this year, mostly south of the border.

The Thursday trip comes one day after Napolitano announced plans to spend more than $400 million to upgrade ports of entry and surveillance technologies to help thwart drugs and arms smuggling along the border.

"Working together at all levels, we take them on and we take them out. That is our goal," Napolitano told reporters after an aerial tour of the border area near San Diego on Wednesday.

From the air, Napolitano could see smugglers' paths worn into the rugged terrain of the Otay Mountains that hug the border. It was the former Arizona governor's first trip to the U.S.-Mexico border since taking office as secretary two months ago.

Besides the $400 million, which is part of President Barack Obama's economic stimulus package approved by Congress, Napolitano has directed her department to step up its outbound inspections. Customs and Border Protection officials would not provide specific details, but said there were about five outbound inspection operations in the past year.

Two weeks ago Customs officials at the eight railroads that go between the U.S. and Mexico began scanning rail cars on the way out of the U.S. instead of just on their way in. When U.S. officials see something suspicious in the X-ray, they alert Mexican law enforcement, which intercepts the rail cars in Mexico.

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